Refrigerant flow controlling device



Aug 30, 1949- D. c. PRINCE I A 2,480,813

REFRIGERANT FLOW CONTROLLING DEVICE Filed Jan 3, 1948 Inventor-r: DavidC. Prince, b9 ZAM; Z, RJ

His Attorney.

Patented Ang.V 30, i949 ,aan

David C. Prince, Schenectady, N. Y., asslgnor to General ElectricCompany, a corporation of New 'gon-k Application January 3, 1948, SerialNo. 25

15 Claims. (Cl. 62-8l My'invention relates to refrigerating systems andmore particularly to flow controlling arrangements for refrigeratingsystems.

In the operation of mechanical refrigerating systems various types offlow controlling arrangements may be employed. For example, float valveshave been utilized for controlling the supply of liquid refrigeranttoevaporators of mechanical refrigerating systems. Such valves provide apositive control of the ilow of refrigerant but it has been necessary toprovide a separate unloading arrangement to allow the compressor motorto come up to speed. An alternative arrangement employs a restrictedtube, sometimes referred to as a capillary tube, between the condenserand the evaporator for controlling the flow of refrigerant. Where suchrestricting `tubes are employed it is not necessary to provide separateunloading means, but another difllculty has arisen in some systemshaving restricting tubes in that, because of the very small diameter ofthe restricting tube, even a small amount of moisture in the system mayfreeze within the tube and block the passage therethrough. By myinvention a flow control device is provided which has the advantage ofthe positive control feature of the float valve and which also combinesprovision for unloading so that a separate unloading device is renderedunnecessary.

Accordingly, it is an object of my invention to provide a refrigeratingsystem including an improved arrangement for controlling the flow ofrefrigerant and for unloading the compressor.

It is another object of my invention to provide an improved owcontrolling device incorporating a, valve and an unloading arrangement.

t is a further object of my invention to provide an improved flowcontrolling device including an arrangement for varying theoperation ofthe device in accordance with changes in condenser temperature orambient temperature.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention .will be pointed out with particularity in theclaims annexed to and forming part of this specification.

For a better understanding of my invention reference may be had to theaccompanying drawing in which Fig. 1 is a generally schematicrepresentation of a refrigerating system incorporating my invention;Fig. 2 is a sectional view of details of the ow controlling devicevshownin Fig. 1; and Fig. 3 illustrates a modification of my invention.

Referring now to Fig. 1, the refrigerating sys# vtem there illustratedincludes a compressor l, a

condenser 2, and an evaporator s. The corn-V pressor is arranged withina hermetically sealed casing t and is driven by a suitable electricmotor (not shown) also included within the hermetically sealed casing 4.Compressed refrigerant is supplied to the condenser through a. conduit 5andl vaporized refrigerant is returned to the casing t' through asuction line 6. Heat is removed from the compressed refrigerant by airpassing over the condenser.

In order to control the iiow of liquid refrigerant from thev condenser 2to the evaporator 3, the

valve l is provided in the liquid line connectingl the condenser and theevaporator. The condenser is connected to the valve through a con-v duit8, and a conduit 9 provides communication between the valve and theevaporator. Y

Within the casing t and von the same shaft' as the compressor l there isarranged a rotary oilv pump I0 which supplies lubricating iluidy to thecompressor. This pump is driven by the same electric motor as isutilized for driving thecompressor i. Lubricating uid is also suppliedfrom l tionary and the lubricating fluid is not under pressure.

In Fig. 2, details of valve 'l are illustrated. The

valve 1 includes a valve body M having a passage' f I5 communicatingwith the conduit 8 and a pase sage i6, communicating with the conduit 9.

Within the valve body adjacent the passages I5 and i6 a seat il isprovided and s. movable valve element i8 is arranged for engagementwiththe seat l?.

The valve includes a housing i9 which is com-y posed of two cooperatinghollow cylindrical parts The part 20 is arranged for screw 20 and 2i.threaded engagement with the valve body It. as

indicated by 22, and the assembly of the valve housing is completed byscrew threaded engagement between the parts 20 and 2l of the housing,

as indicated by 23.

In order to control the movement of the valve element I8 by providing aproper biasing force during operating periods and to remove this bias-'l vlili ing force for unloading purposes during nonoperating periods, acontrol device is arranged within the valve housing I9. The housing part2l provides a chamber 24, and the conduit I3 is connected to the housingin communication with the chamber 24 so that lubricating iluid from thepump I may be supplied to the chamber 24. A hollow Vpiston 25 isslidably received within the chamber 24 and is adapted to be moved underthe influence of the pressure oi the lubricating uid. A cup-shapedmember 26 is also arranged within the housing I9 and is slidablyreceived within the hollow piston 25.

A bellows 21 is secured to the end of the valve element I8 and one endof the bellows is sealed to the valve body I4 as indicated by 28`. Thebellows allows movement of the valve between the open and closedpositions but, by reason ci its being sealed to the valve body I4, iteffectively prevents leakage of refrigerant from the system at the valveelement. In order to transmit motion from the cup-shaped member 26 tothe bellows 21 and to the valve element I8, a calibrating screw 29 isprovided. This screw extends into engagement with a threaded recess inthe end of the cup-shaped member 26 and the head of the screw isarranged to engage the bellows 21 adjacent the end of the valve elementI8. The oppO- site end of the screw 29 engages a compression spring 30which extends internally between the piston 25 and the cup-shaped member26. The calibrating screw may be turned by any suitable wrench insertedthrough an opening 3I in the valve housing to vary the compression onthe spring 30 for normal operation. In order to maintain the compressionspring in position, the hollow piston 25 is provided with an internaltubular guide portion 32 and the cup-shaped member 26 includes acorresponding internal guide portion 33. The guide portions 32 and 33support the spring along the major portion of its length and minimizelateral movement thereof.

In the position shown in Fig. 2, the compression spring exerts a forcetending to bias the valve element I8 to its closed position, the forceexerted being dependent upon the characteristics of the spring. Thus,the valve is maintained in its closed position until the pressuredifferential between the condenser and evaporator exceeds the forceexerted by the spring. Under this latter condition, the valve is forcedto its open position against a bias of the spring, and liquidrefrigerant is supplied to the evaporator until the pressuredifferential is reduced to a value equal to the force exerted by thespring. Thus, the valve maintains a pressure in the condenser sufilcientto effect condensation of the compressed refrigerant supplied by thecompressor I.

When the compressor stops at the end of an operating cycle. it isdesirable to provide for reduction or elimination of the pressuredifferential between the condenser and the evaporator so that, at thebeginning of the next operating cycle, the compressor is permitted tostart under a relatively light load. Should the pressure diierential bemaintained at its normal operating value, the compressor, in starting,would have to supply a refrigerant against the high pressure existing inthe condenser, and this would impose an undesirably heavy load on themotor driving the compressor. By my invention, provision is made forautomatically reducing the pressure in the condenser when therefrigerating apparatus stops at the end of an operating cycle. Duringoperating periods, the piston 25 may be maintained in the position shownin Fig. 2 under the `innuence oi the pressure of the lubricating tluidwithin the chamber 24. When the compressor stops. the pump I0, which isdriven by the same motor as the compressor, also stops, and the pressureof the lubricating iluid is accordingly reduced. Under thesecircumstances, the piston 25 moves to the left. reducing the compressionupon the spring 30. This correspondingly reduces the force exerted bythe spring on the valve element I8, and the pressure differentialbetween the condenser and the evaporator normally maintained by thisvalve is. accordingly reduced. Preferably, an elongated opening 34 isprovided in the cupshaped member 26 and a pin 35, which is threadedthrough an opening in the hollow piston 25, extends into the opening 34.The pin engages an end of the elongated opening to limit the movement ofthe piston to the left. This prevents the piston from engaging the endof chamber 24 and thereby insures the relieving of biasing force on thevalve regardless of whether the spring is completely relaxed or not.

The arrangement described above has the effeet of reducing the condenserpressure and therefore unloading the refrigerating apparatus. Hence,when the compressor starts at the begining of the next operating cycle,it operates under a light load until the pressure of the lubricatingfluid has built up to a suilicient degree to move the piston 25 to theright to the position shown in Fig. 2. During this time, the drivingmotor for the compressor has had an opportunity to come up to theoperating speed and the refrigerating apparatus is able to assume thefull operating load without any overloading of the motor.

It can be seen that by my invention the operation of a controlling valveis modified to provide for unloading and that, as an additional feature.this is accomplished by utilizing an element already required for otherpurposes, namely, the

'lubricating pump of the refrigerating apparatus.

In order to vary the biasing force exerted on the valve with changes intemperature conditions so that the pressure maintained in the condenserwill be satisfactory for the particular temperature conditions involved,a compensating device operated in accordance with changes in temperatureis provided. As illustrated in Fig. 2, the compensating device isarranged to be primarily responsive to changes in the temperature of thecondenser 2; however, the compensating device is also dependent uponchanges in ambient temperature, since such changes' are a primary factorin variations in the temperature of the condenser, which is cooled bythe circulation of air at ambient temperature thereover. Thecompensating device includes a pivoted lever 36. This lever is mountedby a pin 31, and a screw threaded element 38 on a support 39 extendingupwardly from the valve housing I9. The screw threaded element 38engages internal threads within the support 39 in order to provide foradjustment of the position of the pivot pin 39, and hence, of the lever36. This adjustment is provided for calibrating purposes and isprimarily utilized in the initial installation of the compensatingdevice. The pivoted lever 36 includes a plurality of stops or notches40, 4I, 42 and 43 along one face, these stops being disposed adjacent apost 44 extending outwardly from the hollow piston 25. The post 44 isformed integral with a side of ythe piston 25 and extends outwardlythrough an elongated opening 45 in the valve housing I9. For engagementwith the stops on the pivoted lever, an adJustable screw $8 is provided,and this screw extends into engagement with an internal threaded portionof the post tt. The screw t is made adjustable for ealibrating purposesso that it may be adjusted along with the screw threaded element 38during the initial installation of the compensating device.

In order to shift the pivoted lever 35 in accordance with change incondenser temperature, the vconduit t, which is connected to thecondenser, includes a portion di surrounding the main portion of theconduit adjacent thev pivoted lever 3S. The portion dl is secured tothemain portion of the conduit B attt and includes a iianged portion i9which extends into engagement with an end 50 of the pivoted lever 36.The portion dl is composed of a. material having a greatercoemcient ofexpansion than the material of which the main portion of the conduit d'is composed. A

The operation of the compensating device is as follows. Within aparticular range of condensertemperatures. the pivoted lever 3S assumesthe position shown in Fig. 2. In this position, the head of the screw d6has moved to the right along with the piston 25 upon which it ismounted, under the influence of the pressure of the lubricating fluid inthe chamber 2d, and the head of thescrew has come into engagement withstop t2 of the pivoted lever. This stop limits the movement of thepiston 25 and, accordingly, limits the compression of the spring 30resulting from the movement of the piston. Hence, there is apredetermined maximum biasing force on the valve element i8, and acorresponding pressure differential between the condenser and theevaporator is maintained by the valve. Should the condenser temperatureincrease beyond this range. necessitating the operation of the condenserat a somewhat higher pressure, the resulting expansion of the portion dicauses the lower end thereof to move downwardlythereby moving the lever36 in a clockwise direction. This moves the stop d2 upwardly beyond thehead of the screw 66 and allows the piston 25 to move farther to theright under the influence of the pressure of the lubricating uid in thechamber 2li, positioning the head of the screw against the stop d3. Thismovement of the piston 25 further compresses the spring 30 and thereforeresults in an increased biasing force on the valve element i8 and acorresponding increase in the condenser pressure.

Conversely, should the condenser temperature decrease, the pivoted lever36 is moved in a counterclockwise direction by a tension spring 5i toposition either the stop 6l or the stop 40 for engagement by the head ofthe screw t6. It will be noted that this change cannot occur during anoperating period of the apparatus, since the screw 46 preventscounterclockwise movement of the pivoted lever 36 in the position of thepiston 25 shown in Fig.2. The pivoted lever does not shift to its newposition as a result of the decrease in condenser pressure until thepiston 25 has moved to the left to carry the screw 46 beyond the stop 40of the pivoted lever at the end of an operating period. However, sincethe operating period of the apparatus is normally of short duration,particularly as compared to the time required for any substantialambient temperature change which would aiect the operating temperatureof the condenser. this factor does not affect the satisfactory operationof the com pensating device. Y

Fig. 3 illustrates a modiiied arrangement for accomplishing the movementof the pivoted lever in compensating for changes in temperature. Athermostatic bulb 52 is positioned so as to be responsive to condensertemperature or to ambient temperature, and the bulb is connected by atube 53 to an expansible bellows 5t. the bellows being mounted on asuitable stationary support 55. A rod te is connected to themovable wendof the bellows 5t, and the lower end of the rod 5t bears against'apivoted lever 36', correspond--A ing to the lever tt in Fig. 2. yInorder to prevent lateral deflection of the rod, a stationary support 5lis provided, this support including a guide portion 58 for receiving therod 5t.

The operation ofthe modified form shown in Fig. 3 is essentially thesame as that shown in Fig. 2. The bulb 52, as mentioned above, may beplaced so as to be responsive to either ambient temperature or condensertemperature. If the bulb is located so as to be responsive for exampleto ambient temperature, then should the ambient temperature increase,the bellows 5t expands. The rod 56 is moved downwardly by the expansionof the bellows and causes a clockwise .movement of the pivoted lever3E'. This moves stop 42' upwardly and allows the screw d6 to move to theright into engagement with stop 48', increasing the compression on thespring (not shown in Fig. 3) and the biasing force on the movable valveelement i8. Conversely, should the ambient temperature decrease, thebellows contracts and, at the end of the operating period the pivotedlever 3B is moved by the tension spring 5i in a counterclockwisedirection against the end of the rod 5t. The head of the lscrew 46 isthen positioned in engagement with the stop dl' or the stop t0', and thebiasing force on the valve isreduced. v

While I have shown and described specific embodiments of my invention, Ido not desire my invention to be limited to the particular constructionsshown, and I intend by the appended claims to cover all modicationswithin the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A refrigerating system including a compressor, a condenser, and anevaporator, -a valve for controlling flow of refrigerant from saidcondenser to said evaporator, pumping means dependent on the operationof said compressor for supplying iiuid under pressure to said valve, andmeans responsive to the pressure of said iiuid for exerting a forcebiasing said valve toward its closed position ,to maintain a pressuredierential between said condenser and said evaporator.

2. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling ow of refrigerant from said condenser to saidevaporator, means for convveying. fluid from said pump to said valve,and

means responsive to the pressure of said fluid for nexerting a forcebiasing said valve toward its closed position to maintain a pressuredifferential between said condenser and said evaporator.

3. A refrlgerating system including a. compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling owlof refrigerant from said condenser to saidevaporator, means for convey- 75 ing nuid from said pump to said valve,a resilient member for biasing said valve toward its closed position,and means responsive to the pressure of said lubricant for renderingsaid resilient member eiective to maintain a pressure differentialbetween said condenser and said evaporator.

4. A refrigerating system including a compressor, a condenser, and anevaporator, a lubricant pump driven simultaneously with said compressor,a valve for controlling fiow of refrigerant from said condenser to saidevaporator, means for conveying lubricant from said pump to said valve,a spring for biasing said valve toward its closed position, and meansresponsive to the pressure of said lubricant for rendering said springeffective to maintain a pressure diierential between said condenser andsaid evaporator.

5. A refrigerating system including a compressor, a condenser, and anevaporator, a valve for controlling flow of refrigerant from saidconfdenser to said evaporator, a spring for biasing said valve towardits closed position, and means responsive to the operation of saidcompressor for supplying uid under pressure to said valve to increasethe force exerted by said spring, the pressure of said fluid beingreduced upon the stopping of said compressor to reduce the force exertedby said spring whereby the bias on said valve is relieved to unload thecompressor.

6. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling flow of refrigerant from said 'condenser to saidevaporator, said valve including a chamber and a piston within saidchamber, a .spring engaging said piston for biasing said valve towardits closed position, and means for con`- veying uid from said pump tosaid chamber, the pressure of said fluid against said piston acting toshift said piston whereby said spring is rendered effective formaintaining a pressure differential between said condenser and saidevaporator.

'7. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling flow of refrigerant from said condenser to saidevaporator, said valve including a chamber and a piston within saidchamber, a movable valve element, a compression spring arranged betweensaid piston and said movable valve element for biasing said valveelement toward its closed position, and means for conveying fluid fromsaid pump to said chamber, the pressure of said uid against said pistonacting to shift said piston whereby said spring is rendered effective tomaintain a pressure differential between said condenser and saidevaporator.

8. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling ilow of refrigerant from said condenser to saidevaporator, means for conveying fluid from said pump to said valve,means responsive to the pressure of said fluid for exerting a forcebiasing said valve toward its closed position to maintain a pressuredifferential between saidcondenser and said evaporator, andtemperature'responsive means for limiting the4 biasing force on saidvalve.

9. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling flow of refrigerant from said .condenser to saidevaporaton means for conveying fluid from said pump to said valve, meansresponsive to the pressure of said uid for exerting a force biasing saidvalve toward its closed position to maintain a pressure differentialbetween said condenser and said evaporator, and means responsive toambient temperature for limiting the biasing force on said valve.

11. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling flow of refrigerant from said condenser to saidevaporator, said valve including a chamber and a piston within saidchamber, means for conveying fluid from said pump to said chamber, saidpiston being movable under the pressure of said fluid to introduce aforce biasing said valve toward its closed position, said pistonincluding a portion projecting beyond said chamber, and means responsiveto the temperature of said condenser for engaging said portion to limitthe movement of said piston whereby the biasing force exerted on saidvalve is limited.

12. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling flow of refrigerant from said condenser to saidevaporator, said valve including a chamber and a piston within saidchamber, means for conveying uid from said pump to said chamber, saidpiston being movable under the pressure of said fluid to introduce aforce biasing said valve toward its closed position. said pistonincluding a portion projecting beyond said chamber, and means responsiveto ambient temperature for engaging said portion to limit the movementof said piston whereby the biasing force exerted on said valve islimited.

13. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven' simultaneously with said compressona valvefor controlling flow of liquid refrigerant from said condenser to saidevaporator, said valve including a chamber and a piston movable Withinsaid chamber, means for conveying fluid from said pump to said chamber,said piston being movable under the pressure of said fluid to introducea force biasing said valve toward'its closed position, said pistonincluding a portion projecting beyond said chamber, and a pivoted level'mounted adjacent said portion and movable in response to changes in thetemperature of said condenser, said pivoted lever including a pluralityof stops for engaging said portion of said piston in a plurality ofpositions for varying the biasing force exerted on said valve.

14. A refrigerating system including a condenser, a compressor and anevaporator, a pump driven simultaneously with said compressor, a. valvefor controlling the flow of refrigerant from said condenser to saidevaporator, said valve including a, chamber and a piston movable withinsaid chamber, said piston including a portion extending beyond saidchamber, a pivoted lever mounted adjacent said portion of said piston.and

15. A refrigerating system including a compressor, a condenser, and anevaporator, a pump driven simultaneously with said compressor, a valvefor controlling iiow of refrigerant from said condenser to saidevaporator, said valve including a. chamber and a piston movable withinsaid chamber, means for conveying iiuid from said pump tosaid chamber,said piston being movable under the pressure of said fluid to introducea force biasing said valve toward its closed position, said pistonincluding a portion projecting beyond said chamber, a pivoted levermounted ad jacent said portion of said piston, said pivoted leverincluding a plurality of stops for engaging said piston in a pluralityof positions of said piston, and an expansible bellows arranged toengage said pivoted lever, said expansible bellows being responsive toambient temperature for moving said pivoted lever to vary-the positionof said piston whereby the biasing force exertedon said valve is varied.

- .DAVID C. PRINCE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,304,316 Newton Dec. 8, 1942 202,453,439

Hubbard Nov. 9, 1948

